Bangkok - Lee Westwood displayed all his class and experience on Sunday as he brushed aside a challenge from Masters champion Charl Schwartzel to win the $1 million Thailand Golf Championship by seven strokes.
The emphatic victory at the Amata Spring Country Club, Westwood's fourth of the season, moved him up to world No 2, replacing Rory McIlroy.
The Englishman had played fine golf all week including a stunning 12-under-par 60 in the first round.
He shot 69 in his final round to finish the tournament on 266, an impressive 22 under par, for his third win in Asia this season.
Schwartzel fought hard and briefly threatened the leader, but the South African had to settle for the runner-up spot after shooting an even-par 72.
Little-known American Michael Thompson performed well with a 70 to finish in third place, one shot back, while in joint fourth place two strokes further behind were Thailand's Chawalit Plaphol and Simon Dyson of England.
Schwartzel began the day knowing he had to overhaul a four-shot lead and got off to a good start when he birdied the first hole, while Westwood could only manage a par.
But Westwood responded quickly with two successive birdies and at the turn the Englishman held a five-shot lead.
There was drama at the par-five 11th when Schwartzel sunk an eagle while Westwood missed a birdie putt, resulting in a two-shot swing to the South African and cutting the lead to three.
Both players birdied the 12th but Westwood also picked up a stroke at the 13th to restore his four-shot lead.
Schwartzel's challenge effectively ended at the next hole when a poor chip saw him make a bogey, leaving Westwood five shots clear with just four to play. He went on to stretch the lead by a further two strokes.
John Daly finished joint 16th after shooting 75 in the final round while Sergio Garcia recorded a 71 for joint 24th place.
Japanese star Ryo Ishikawa finished what was a miserable tournament for him with a 73, well down the field on a total of 297, nine over par.
Ishikawa was in good company though, sharing the same overall score as British Open champion Darren Clarke who shot a disappointing 77 in his final round.
Final scores at the $1million Thailand Golf Championship at the par-72 Amata Spring Country Club course:
266 - Lee Westwood (ENG) 60-64-73-69
273 - Charl Schwartzel (RSA) 69-66-66-72
274 - Michael Thompson (USA) 69-66-69-70
276 - Chawalit Plaphol (THA) 73-61-65-67, Simon Dyson 69-70-68-69
279 - Daisuke Maruyama (JAP) 73-68-68-70 Guido Van Der Valk (NED) 71-69-66-73
280 - Alex Cejka (GER) 71-71-71-67
281 - Tetsuji Hiratsuka (JAP) 71-72-68-70, Jeev Milkha Singh (IND) 71-68-72-70
282 - Gregory Bourdy (FRA) 68-71-72-71, Prom Meesawat (THA) 72-68-69-73
283 - Jyoti Randhawa (IND) 73-70-65-75
284 - Prayad Marksaeng (THA) 71-74-70-69, Chinnarat Phadungsil (THA) 72-69-72-71
285 - John Daly (USA) 65-73-72-75, Rikard Karlberg (SWE) 72-71-66-76
286 - Scott Barr (AUS) 72-71-69-74
287 - Thorbjorn Olesen (DEN) 72-73-72-70, Thaworn Wiratchant (THA) 68-73-73-73, Quincy Quek (SIN) 74-69-71-73, Lu Chien-soon (TPE) 69-71-73-74, Atthaphon Prathummanee (THA) 71-74-68-74
288 - Thanyakon Khrongpha (THA) 71-73-74-70, Jonathan Moore (USA) 73-69-77-69, Sergio Garcia (ESP) 76-71-70-71
297 - Ryo Ishikawa (JAP) 70-77-77-73, Darren Clarke (NIR) 71-76-73-77